瓜伊马斯盆地热液区深部沉积物中甲烷及其他小分子化合物的代谢途径与机制研究

海洋沉积物是地球上最大的有机碳库，为深部生物圈微生物提供了巨大的栖息地。小分子化合物（如挥发性脂肪酸和一碳化合物等）是有机质降解过程中产生的重要中间产物，可以为深部生物圈中的产甲烷菌及其他微生物提供碳源和能量来源。因此，小分子化合物的代谢在深部生物圈微生物介导的生物地球化学循环过程中起着至关重要的作用。本项目以瓜伊马斯盆地热液区的深部沉积物为研究对象，结合地球化学分析、放射性同位素示踪、热力学计算以及分子生物学等多种生物地球化学和地质微生物学的交叉技术手段，对深部生物圈中甲烷及其他小分子化合物的生成及代谢机制进行系统研究，阐明温度、压力、地化条件、沉积环境以及岩床入侵等因素等对产甲烷过程和小分子代谢途径的影响，揭示小分子化合物代谢在深部生物圈和全球碳循环中所起到的重要作用。该项目的开展将有助于进一步拓展目前对深部生物圈能量代谢途径的认识，深入了解深部生物圈中微生物介导的生物地球化学循环。

Marine sediment is the largest organic carbon reservoir on Earth, providing a vast habitat for deep biosphere microorganisms. Low molecular weight (LMW) compounds (e.g. volatile fatty acids, C1 compounds) are important intermediates during organic matter degradation and these substrates can provide energy and carbon sources for methanogens and other microbes. Therefore, the metabolism of LMW carbon substrates plays an important role in microbially mediated biogeochemical cycles in the deep subseafloor sediment. This proposal will focus on the generation and metabolism of methane and other LMW compounds in the hydrothermally impacted deep sediments of Guaymas Basin. We will integrate geochemical measurement, radioisotope labelling, thermodynamic calculations and molecular analysis to reveal environmental factors (e.g. temperature, geochemical gradients, sedimentary settings and sill intrusion) affecting the metabolic pathways and decipher the role of LMW metabolism in the deep biosphere and global carbon cycling. The results from this project will further extend our understanding on the energy strategy, metabolic pathways and biogeochemical cycling in the deep biosphere.